This invention relates to an exercise device that can be used by a person to strengthen his/her leg and foot muscles. The device comprises a base structure placeable on the floor, and two platforms that are hingedly connected to the base structure for swinging motions around a horizontal axis near one edge of the base structure. Each platform has an internal spring means for normally biasing the platform upwardly to an inclined position. The two platforms are spaced apart so that the person can stand with one foot on each platform. The platforms are individually depressible to horizontal positions by exerting pressure thereon through the muscles of the feet and ankles.
This exercise device will be helpful to any person desiring to increase muscular development in his/her feet or ankles, especially athletes desiring to jump higher and/or run faster.
The device of this invention is somewhat like the device shown in U.S. Pat. No. 4,111,416 to W. Jinotti. The Jinotti device includes a foot-supporting platform having a coil spring means therein. The spring is non-adjustable, such that the device cannot be set for effective use by different persons having different muscle strengths. My invention contemplates the use of an adjustable strength spring means in each platform, whereby the device can be used by different persons, and by persons for prolonged periods while their muscle strength is developing (changing).
U.S. Pat. No. 4,804,180 shows an exercise device that includes a swingable foot pedal having a tension coil spring associated therewith. Opposite ends of the coil spring can be inserted into selected holes in a first stationary angle iron and spaced holes in a second angle iron attached to the foot pedal. By inserting the spring ends into different holes it is possible to vary the spring tension and thus the resistance offered by the pedal to downward foot pressure. One problem with the arrangement of U.S. Pat. No. 4,804,180 is that the spring will usually be under considerable tension so that the process of removing the spring ends from the holes and attaching them to different holes is not easily accomplished. Also, there is the danger that during the process of removing or attaching the springs the person might temporarily loosen his grip on the spring so as to be injured by a fast-moving spring end. My invention contemplates the use of screw-actuated adjustment devices for the springs; adjustment of the spring force is easily accomplished by turning a manual adjustment knob connected to the screw. There is no need to manually readjust the spring location, as in the device of U.S. Pat. No. 4,804,180.